1. Field of the Invention
The present invention relates to inclusion complexes of glipizide with cyclodextrin in presence of a nonionic surfactant. The invention also discloses a method for preparing such inclusion complexes, as well as pharmaceutical compositions containing the inclusion complex, in combination with pharmaceutically acceptable excipients.
More particularly the invention relates to inclusion complexes of glipizide preferably micronised with cyclodextrin or a cyclodextrin derivative in the presence of a nonionic surfactant, and pharmaceutical compositions there of.
2. Related Art 
Glipizide of the formula 1 is an oral blood glucose lowering drug of the sulfonyl urea class. The chemical abstracts name of glipizide is 1-cyclohexyl -3-[[p-[2-(methylpyrazinecarboxamido)ethyl]phenyl]sulfonyl]urea. The molecular formula is C21H27N5O4S; and the molecular weight is 445.55. Glipizide is a whitish, odorless powder with pKa of 5.9. It is insoluble in water and alcohol but soluble in 0.1N NaOH.
Glipizide is a hydrophobic drug with poor aqueous solubility at room temperature. Also, glipizide being a weakly acidic drug, its aqueous solubility in the acidic pH of gastric juice is even less. Hence, after oral administration the drug is likely to be absorbed only in the lower path of gastrointestinal tract. This probably explains the protracted onset of biological effect of glipizide, although other theories are possible to explain this observation.
For rapid onset of action of glipizide during high blood glucose level conditions, high bioavailability is required which in turn is achieved by high aqueous solubility thereof. In order to achieve aqueous solubility and hence maximum absorption of the drug glipizide, so that it exhibits good pharmacological behavior, inclusion complexes of glipizide with cyclodextrin or cyclodextrin derivatives are prepared. Such rapid dissolving drug formulations of glipizide can be timed to meal taking events.
One aspect of the invention is to provide an inclusion complex of glipizide and a nonionic surfactant with cyclodextrin, or a derivative thereof, which is safe for use as a pharmaceutical composition, renders the active drug glipizide highly soluble in physiological pH as well as in gastric fluid pH, and permits rapid dissolution of the active drug glipizide in physiological pH as well as in gastric fluid pH.
Another aspect of the invention is to provide a method for preparing an inclusion complex of glipizide and a nonionic surfactant with cyclodextrin, or a derivative thereof, which results in a product safe for use as a pharmaceutical composition. Such a method is simple, less time consuming than conventional techniques, efficient and economical, and which renders the active drug glipizide highly soluble in physiological pH as well as in gastric fluid pH and also permits rapid dissolution of the active drug glipizide in physiological pH as well as in gastric fluid pH.
Another aspect of the invention is to provide a method for preparing an inclusion complex of glipizide and a nonionic surfactant with cyclodextrin, or a derivative thereof which is suitable for manufacture of a product on commercial scale. p Another aspect of the invention is to provide a pharmaceutical composition containing an inclusion complex of glipizide and a nonionic surfactant with cyclodextrin, or a derivative thereof, that is safe for use as a pharmaceutical, renders the active drug glipizide highly soluble in physiological pH as well as in gastric fluid pH, and permits rapid dissolution of the active drug glipizide in physiological pH as well as in gastric fluid pH.
Another aspect of the invention is to provide a method for the preparation of pharmaceutical compositions of an inclusion complex of glipizide and nonionic surfactant with cyclodextrin which results in a product safe for use as a pharmaceutical, renders the active drug glipizide highly soluble in physiological pH as well as in gastric fluid pH, and permits rapid dissolution of the active drug glipizide in physiological pH as well as in gastric fluid pH.